Field of the Invention
The present invention relates to furnaces and particularly to a sound reduction enclosure attached to a furnace which reduces the sound of the combustion process taking place inside of the furance.
Room air may be heated by passing a forced draft over the combustion system of a furnace and then returning the air in heated condition to the room. Typically, a combustible fuel gas and combustion air are admitted into a combustion chamber of a furnace. In a design for which the invention is particularly adapted, the furnace includes a compact generally cylindrical cast combustion chamber having a single port inshot target burner disposed therein. The gas-air mixture is ignited within the combustion chamber, producing a turbulent flame with resultant generation of heat. The combustion products pass through a heat exchanger and are vented to the atmosphere. The agitation of the burner flame, which is necessary to satisfy combustion and performance requirements, generates noise at a level which is undesirable for commercial or residential applications.
Considerable effort was given to muffling the sound to acceptable levels for consumer acceptance. Criteria met by the invention were (1) the sound is effectively muffled without interfering with the air and gas mixing in a manner that would adversely affect burner performance and (2) the sound muffling arrangement effectively contains noise emission from the combustion chamber and avoids harmonic/pure tone resonance.